Not more than two successive doubled studs bored in exterior walls may be bored to what percentage of their width?

When considering the structural integrity of exterior walls, particularly in relation to doubled studs, it's important to adhere to specific guidelines regarding the allowable boring of these members. Doubling studs are critical in providing support and stability in wall assemblies, and excessive boring could compromise their strength.

The standard allows for not more than two successive doubled studs to be bored to a maximum of 60% of their width. This guideline ensures that there is enough material remaining to maintain the load-carrying capacity of the studs. By restricting borings to this percentage, it mitigates risks associated with structural failure due to over-weakening the studs from excessive removal of their material.

Choosing a higher percentage, such as 70% or 80%, would increase the risk of structural compromise, as it could potentially reduce the load-bearing capability of the studs beyond acceptable limits. Thus, adhering to the 60% guideline strikes a balance between functional requirements—such as electrical and plumbing installations—and the necessary strength needed for building stability.

This standard is rooted in engineering principles that prioritize safety and durability in construction, reflecting best practices in the building inspection field.